1. Field of the Invention
The present invention is directed to apparatus for receiving tools. More particularly, the present invention is directed to apparatus for receiving and holding tools, such as welding units associated with welding installations. Specifically, the present invention is directed to apparatus for receiving and holding resistance welding tools mounted in welding installations which are used in automated assembly lines which include one or more robots for carrying out a series of operations, such as spot welding.
2. Description of Background Information
In conventional welding installations, each welding unit is mounted or otherwise carried by a robot which applies a series of movements to the welding unit that it carries which correspond to the various spot welds to be executed. The installation includes a station where the robot deposits the welding unit at a specific location, disconnects the unit and couples itself to another welding unit or device, for example when different tasks are executed on the line.
The locations along the welding installation provided for receiving and taking up tools are disposed in areas situated outside the working area of the robot but in a restricted area to which access by personnel is barred for reasons of safety. Should the need arise for a person to enter the restricted areas, all the robots must be shut down completely. Consequently, the installations include various safety systems for barring access to restricted areas while the robots are operating. An installation of this kind, however, has a number of disadvantages, as discussed further herein below.
A robot is characterized by the maximum load that it can move. Although an integrated coupling and decoupling system significantly increases the mass which can be moved by the robot, such integrated systems often lead to premature wear of the robot. Should a robot break down, it is extremely difficult, if not impossible, to disconnect its tools because the coupling and decoupling mechanism is usually operated by a pressurized fluid, such as hydraulic fluid, and when pressure is lost, because of break down or shut down, it is difficult and often impossible to activate the fittings required to release the tools.
In any event, while the robot is in operation, it is impossible to manually operate, work on or repair the tools even on a tool that is not in use, because the tools are in a restricted area. Consequently, it is not possible to service or replace a tool that is not being used while the assembly lines including the robots are in operation. Nevertheless, service, maintenance, repair, such as electrode changing, and other operations are routinely required, and it is necessary to shut down the robots in order to perform these functions. Such down-time naturally reduces productivity of the line.
Although consideration has been given to providing means for decoupling the tools from the robot and means for coupling the tools to the robot in the restricted areas or locations intended to receive the tools so as to avoid any unnecessary increase in the weight of the robot, this kind of arrangement still has some of the previously discussed disadvantages.
The present invention provides a device which alleviates the various disadvantages described above.